Community antenna television (CATV) systems and many broadband data transmission systems rely on a network of coaxial cables to carry a wide range of radio frequency (RF) transmission with low amounts of loss and distortion. A covering of plastic or rubber adequately seals an uncut length of coaxial cable from environmental elements such as water, salt, oil, dirt, etc. However, the cable must attach to other cables and/or to equipment (hereinafter, “ports”) for distributing or otherwise utilizing the signals carried by the coaxial cable. A service technician or other operator must attach a coaxial cable connector (hereinafter, “connector”) to the cut and prepared end of a length of coaxial cable in order to mate the coaxial cable to the port. This is typically done in the field. Environmentally exposed (usually threaded) parts of the connectors and ports are susceptible to corrosion and contamination from environmental elements and other sources, as the connections are typically located outdoors, at taps on telephone polls, on customer premises, or in underground vaults. These environmental elements eventually corrode the electrical connections located in the connector and between the connector and mating components. The resulting corrosion reduces the efficiency of the affected connection, which reduces the signal quality of the RF transmission through the connector. Corrosion in the immediate vicinity of the connector-port connection is often the source of service attention, resulting in high maintenance costs.
Numerous methods and devices have been used to improve the moisture and corrosion resistance of connectors and connections. These include, for example, wrapping the connector with electrical tape, enclosing the connector within a flexible boot which is slid over the connector from the cable, applying a shrink wrapping to the connector, coating the connector with plastic or rubber cement, and employing tubular grommets of the type discussed in U.S. Pat. No. 4,674,818 (McMills et al.) and in U.S. Pat. No. 4,869,679 (Szegda), for example.
Although these methods work, more or less, if properly executed, they all require a particular combination of skill, patience, and attention to detail on the part of the technician or operator. For instance, it may be difficult to apply electrical tape to an assembled connection when the connection is located in a small, enclosed area. Shrink wrapping may be an improvement under certain conditions, but shrink wrap application typically requires applied heat or chemicals, which may be unavailable or dangerous. Rubber-based cements eliminate the need for heat, but the connection must be clean and the cement applied somewhat uniformly. These otherwise attainable conditions may be complicated by cold temperatures, confined or dirty locations, etc. Operators may require additional training and vigilance to seal coaxial cable connections using rubber grommets or seals. An operator must first choose the appropriate seal for the application and then remember to place the seal onto one of the connective members prior to assembling the connection. Certain rubber seal designs seal only through radial compression. These seals must be tight enough to collapse onto or around the mating parts. Because there may be several diameters over which the seal must extend, the seal is likely to be very tight on at least one of the diameters. High friction caused by the tight seal may lead an operator to believe that the assembled connection is completely tightened when it actually remains loose. A loose connection may not efficiently transfer a quality RF signal causing problems similar to corrosion.
Other seal designs require axial compression generated between the connector nut and an opposing surface of the port. An appropriate length seal that sufficiently spans the distance between the nut and the opposing surface, without being too long, must be selected. If the seal is too long, the seal may prevent complete assembly of the connector. If the seal is too short, moisture freely passes. The selection is made more complicated because port lengths may vary among different manufacturers.
In view of the aforementioned shortcomings and others known by those skilled in the art, the inventor has recognized a need for a seal and a sealing connector that addresses these shortcomings and provides other advantages and efficiencies.